M-net calculus based semantics for triggers

Abstract

A formal semantics for the trigger concept in active data base systems is proposed. Such data base systems have the capability to react to the occurrence of some events, allowing to execute automatically some treatments. These capabilities to react are given by adding to the data base system a set of production rules, called triggers. During the last decade, a lot of works have been devoted to the design and implementation of triggers in data base systems leading to the generic field of active data bases. While the idea of using Petri nets to give a semantics for triggers has already been pointed out, the existing works either only suggest such a use and does not show how to do it, or capture only a very small part of the execution model. Also, they lack the use for high-level Petri nets only able to provide a concise net semantics. In this paper we propose to extensively make use of a specific kind of high level Petri nets: the M-nets. Such nets, allowing for compositionality appear particularly well-suited to give a formal semantics for the general Event Condition Action (ECA) model of triggers.